Task3_TimeWatch for game condition

1. Introduction

For this week, I have worked on some new condition which can limit players play time. 

At the beginning, I thought about HP. However, I already used this function many times in the previous course.

Consequently, I have played one of my classmates game and that game has time limitation. Once the time is equal or less than 0. The game end.

It is simple and clean l believe.

2. Goal

- Setting time

- Update on UI

- Add condition to the players (or more)

3. Problem

I have problems with current time. I want it to stop count down time when it reach 0.

However, it goes to the negative number. After reading some documents. I came with answer just state my currentTime. = 0;

when time reaches 0.